94 INVESTIGATION OF THEORY IMPORTUNED. 



and combined. The latitude is exercised of effecting not only 

 a chemical union by tlie poles inappropriate to the formation of 

 radiant light, but also with those which are the sole and pecu- 

 liar poles by the combination of which light can alone be con- 

 stituted ; and this affords a great and immense amplitude of 

 combination which occasions that variety so evident in the 

 constitution and properties of fixed bodies generally, in the 

 animal, vegetable, and mineral kingdoms ; and to such an 

 extent of diversification is it carried, that no exact duplicate 

 can be found of anything in nature. 



To the youthful tyro who may be one to indulge me by 

 the perusal of these pages, I must observe, that nothing can 

 be with propriety admitted as an established law in a system 

 of science until supported by a train of incontrovertible facts, 

 in testimony of its rectitude, and therefore the strongest scru- 

 tiny is advisable on the advance of novel views, lest the pro- 

 jector may have been led away by sanguine opinions of his 

 premises, and which might terminate in fallacious conclusions. 



It is not to establish theoretic views, but to induce investi- 

 gation that they are now advocated, as such inquiry (if serious 

 and persevering) may lead to valuable results. 



r &/ J . Hit) 



ABSORPTION AND DISCHARGE OF LIGHT WITHOUT 

 COMBUSTION. 



LIGHT appears to enter into some bodies of a particular 

 description, from which it may be disengaged without the aid 

 of heat, or evident combustion, as shown by the early experi- 

 ments of Father Beccaria on bodies which, when exposed to 

 light become luminous, and when removed to a dark room, 

 give out their light for some time, and this property is renewed 

 in those bodies by fresh exposure to the influence of light. 



Such is Canton's pyrophorus, or dry phosphorus, composed 

 of oyster-shell lime and sulphur, exposed to a red heat for an 

 hour. 



